Slump block producing machine



Sept. 27, 1966 B. 1.. MIZER ETAL 3,274,660

SLUMP BLOCK PRODUCING MACHINE Filed Oct. 17, 1960 2 Sheets-Sheet 1 INVEN TORS B/AL L. M/ZEE 205E197 7f/W/ZEE-v4/Vfl- DOA/4A0 E. W/l/TEAZ/ESTSept. 27, 1966 Filed Oct. 17. 1960 B. L. MIZER ETAL SLUMP BLOCKPRODUCING MACHINE 2 Sheets-Sheet 2 United States Patent 3,274,660 SLUMPBLOIIK PRODUCING MACHINE Bill L. Mizer, Phoenix, Robert T. Mizer,Scottsdale, and Donald E. Whitehurst, Phoenix, Aria, assignors toBuilders Equipment Company, a corporation of Arizona Filed Oct. 17,1960, Ser. No. 63,040 4 tclaims. (Cl. 2541) This invention relates to aslump block producing machine and more particularly to a slump blockproducing machine capable of producing slump blocks of blocks formed bya conventional high production concrete production machine immediatelyafter the conventionally formed blocks have been delivered therefrom.

The term, slump block, as used herein, defines a concrete block producedfrom mortor containing a slightly greater amount of moisture than isnormally used in conventional concrete blocks and the term, slump blocalso defines a block, the side wall surfaces of which, are slightlybowed or slumped outwardly of flat vertical planes common toconventional high production concrete blocks.

Slump blocks are sometimes desirable from an architectural standpointsince they have uneven contoured surfaces and tend to break the monotonyof conventional smooth flat surfaced block or wall construction.

It has heretofore been a problem to produce slump blocks on highproduction concrete block producing machines such as the well-knownBesser machines. These machines normally produce very accurate smoothstraight sided blocks at a very high rate, and most concrete blockproducing plant operators have recognized the desirability of utilizingsuch machines for producing slump blocks so that separate facilities maynot be needed to produce these slump blocks. It has been a problem toprovide means usable in connection with such high production machineswhich will convert the accurate blocks, thus produced, into slump blocksat a production rate approximating or normal to that of the highproduction machine.

Concrete block producing machines normally deliver several concreteblocks on rather extensive pallets and the blocks must be produced sothat they have an excessive vertical dimension in order that they maysubsequently be compressed into slump blocks. Considerable diflicultyhas been encountered in performing this operation and at the same timeachieving uniform height of the slump blocks throughout the over-allarea of the pallet on which the blocks are delivered. Additionally,great difiiculty has been encountered in forcing blocks, produced by ahigh production machine, into slump configuration within the timeallowed during each cycle of operation of such a concrete blockproducing machine.

Accordingly, it is an object of the invention to provide a slump blockproducing machine which is located to compress blocks delivered by aconventional high production block machine into slump blocks at a ratecompatible with the operation of the concrete block producing machine.

Another object of the invention is to provide a very simple slump blockproducing machine which may readily be located above and in adjacentrelationship with the conventional delivery conveyor of a highproduction concrete block producing machine.

Another object of the invention is to provide a slump block producingmachine having a novel means for suspending and vertically actuating apressure plate which is utilized to compress conventional concreteblocks into slump blocks over the delivery conveyor of a high prodnctionconcrete block producing machine.

Another object of the invention is to provide a slump block producingmachine having novel means for supporting a block laden pallet on thedelivery conveyor of a high production concrete block machine whileproducing vibration of the pallet which supports blocks thereon, andwhile a pressure plate is concurrently vibrated and forced downwardly onthe upper surfaces of blocks so that they are quickly converted fromconventional high production concrete blocks into high production slumpblocks.

Another object of the invention is to provide a slump block producingmachine operable above and adjacent to the delivery conveyor of a highproduction concrete block producing machine and wherein novel means isprovided for actuating and leveling a pressure plate, which engages theupper sunfaces of several blocks carried by a pallet on said conveyorwhereby, engagement of said pressure plate with said blocks isaccurately controlled evenly to apply vertical force on said blocks sothat they are uniformly and accurately compressed into slump blockconfigurations.

Further objects and advantages of the invention may be apparent from thefollowing specification, appended claims and accompanying drawings inwhich:

FIG. 1 is a side elevational view of a slump block producing machine ofthe present invention shown supported on the delivery "conveyor framestructure of a conventional high production concrete block producingmachine.

FIG. 2 is an enlarged fragmentary sectional view taken from the line 22of FIG. 1.

FIG. 3 is a side elevational view of a slump block showing by brokenlines, the relative outline and dimensions of an original highproduction concrete block from which the slump block is produced.

FIG. 4 is a fragmentary sectional View taken from the line 44 of FIG. 1.

FIG. 5 is an enlarged fragmentary sectional view taken from the line 55of FIG. 4; and

FIG. 6 is a fragmentary sectional view taken from the line 66 of FIG. 4.

As shown in FIG. 1 of the drawings, the slump block producing machine ofthe invention is provided with a suspension frame 10 secured by bolts'12 to an output conveyor frame 14 of a conventional high productionconcrete block producing machine. Supported between the members '14 is across member 16 having upstanding members 18 which support rails 20.

Mounted on these rails 20 are rollers 22 which support conventionalflexible pallet delivery belts 24. These belts 24- move pallets 26 awayfrom the conventional high production concrete block machine and thebelts are similar to those employed in connection with the conventionalBesser concrete block producing machines.

The belts 24 are slightly resilient and also slightly compressible.According to the present invention, stop bars 28 are located at a levelslightly below the lower surface of the pallet carried by the belts 24.As shown in FIG. 5 of the drawings, these bars 28- are provided withupper surfaces 30 which may be a small fraction of an inch below thenormal upper surfaces 3-2 of the belts 24. The upper surfaces 30 of thebars 28 are adapted to support the pallet 26 when pressure is exerted onblocks carried by the pallet during the process of creating slumpblocks. When such pressure is exerted on the pallet 26, the belt 24 isslightly compressed whereupon the lower surface 34 of the pallet 26engages the upper surface 30 of the bars 28, all as will be hereinafterdescribed in detail.

Mounted on the cross bar 16 is a vibrator assembly 36 comprisingpivotally mounted vibrators 38 and 40. These vibrators 38 and 40 arepneumatically operated vibrators coupled to a compressed air supply tube42. The assembly 36 is provided with a pair of pivot pins 44 and 46 uponwhich the vibrators 38 and 40, respectively, are mounted. Thesevibrators are thus pivotally mounted so that they may move into brokenline positions A when a laden pallet 26 moves thereover in a directionas indicated by the arrow B, all as shown in FIG. 2 of the drawings.

Coupled to the vibrators 38 and 40 are pallet engaging members 48 and 50disposed to engage the lower surface 34 of each pallet 26 as it passesthereover in the direction of the arrow B. These pallet engaging members48 and 50 are provided with curved surfaces 52, as shown in FIG. 2 ofthe drawings, whereby engagement of the pallet 26 therewithautomatically pivots these members and the respective vibrators into thebroken line position A, shown in FIG. 2 of the drawings. When pivotedinto such position, the curved surface 52 continues to engage the lowersurface 34 of the pallet 26 since gravity tends to act upon thevibrators 38 and 40 in a manner to maintain efficient contact of theengaging members 48 and 50 with the lower surface 34 of the pallet 26.Thus, the vibrators 38 and 40 transmit vibration to each pallet 26 as itpasses thereover and into position below a compression plate 54, shownin FIGS. 1 and 4 of the drawangs.

The pressure plate 54 is supported by a frame 56 and is coupled to aplunger 58 of a fluid cylinder 62 by means of a clevis pin 60. The fluidcylinder 62 is pivotally supported and suspended by a bolt 64 extendingthrough cross member 66 of the suspension frame 10.

Thus, the pressure plate 54 is pivotally suspended from the bolt 64 andis thus capable of freely aligning with upper surfaces of concreteblocks carried by the pallet 26 supported on the belts 24, herein beforedescribed.

Cross arms 68 of the suspension frame 10 support coil springs 70 whichare coupled to the frame 56 and resiliently lend support and suspensionstability thereto.

Mounted on the frame 56 are pneumatic vibrator motors 72 and 74 whichare coupled to the compressed air conduit 42, as will be hereinafterdescribed in detail.

The pressure plate frame 56 is provided with adjustable stop screws 76.Four of these screws 76 are provided and disposed to bear at their lowerends upon rails 78 and 80, carried by the members 14, shown best in FIG.1 of the drawings. The lower ends of the stop screws 76 provide a fixedstop for the pressure plate 54 relative to the pallet 26 in orderaccurately to control the height of slump blocks produced in accordancewith the present invention. These stop screws 76 are verticallyadjustable to provide the precise parallel alignment of the pressureplate 54 relative to a pallet 26 therebelow.

Four springs 82 are carried by the pressure plate frame 56 and extenddownwardly to a position slightly below the lower ends of the stopscrews 76 whereby they provide initial leveling of the frame 56 as itmoves downwardly. The lower ends of these springs 82 first engage therails 78 and 80 in order to pivotally align the pressure plate frame 56in substantially parallel relation with the upper surfaces of blockscarried by the pallet 26 before the pressure plate 54 engages theseblocks. In operation, the springs 82 are compressed during the downwardmovement of the frame 56 until the lower ends of the adjusting screws 76engage the rails 78 and 80.

Fixed to a bar member 84 of the frame 10 is a sleeve 86 having a rod 88adjustably mounted therein. A set screw 90 screwthreadably connected tothe sleeve 86 is disposed to fix the rod 88 in various adjustedpositions therein, as desired.

Supported on the lower end of the rod 88 is a limit switch 92 having acontact roller 94 engageable with an arm 96 which is fixed to theplunger 58 by means of a jam nut 98. The arm 96 is provided with an endportion 100 adapted to contact the roller 94 for operating the switch92, which is also shown schematically in FIG. 1 of the drawings.

The roller 94 is disposed to be engaged by the end portion 100 of thearm 96 when the pressure plate 54 has been extended downwardly to apredetermined position a few thousands of an inch above a location atwhich all of the stop screws 76 bear solidly upon the rails 78 and 80,all as will be hereinafter described relative to the operation of theslump block producing machine of the invention.

The cylinder 62 is operated by compressed air which communicates througha tube 102 with the upper end of the cylinder 62 and through a tube 104connected to the lower end of the cylinder 62. The plunger 58 isprovided with a double acting piston 114 so that it may be powereddownwardly or upwardly according to operation of a solenoid valve 106.

This valve 106 communicates with a compressed air supply tube 108 and isa normally closed valve disposed to furnish a supply of air underpressure to the tube 102 and the tube 42 for energizing the cylinder 62and the vibrators 38, 40, 72 and 74. Thus, the solenoid valve 106, whenenergized, supplies compressed air to the upper end of a cylinder 62tending to force the plunger downwardly and at the same time energizesall of the hereinbefore mentioned vibrators.

Interconnecting the tube 108 and the tube 104 is a pressure regulator110. This pressure regulator reduces pressure of compressed air from thetube 108 to the tube 104 so that air acting on a lower surface 112 ofthe piston 114 is less than that acting on the upper surface 116thereof. It will be understood that when the solenoid valve is innormally closed position, air pressure is exhausted from the upper side116 of the piston 114 due to the fact that the air pressure acting onthe lower side 112 causes the piston to move upwardly and to exhaust theremaining air in the cylinder outwardly through the tube 102, tube 42,and to the vibrator motors 38, 40, 72 and 74. Further, it will beunderstood that when the solenoid valve 106 is open, air pressure in thetube 102 is greater than air pressure in the tube 104, the piston 114 isforced downwardly in the cylinder 62 thereby overcoming regulated airpressure acting on the side 112 of the piston 114, whereupon the frame56 is moved a short distance downwardly in order to permit the pressureplate 54 to exert force on blocks carried by a pallet 26 to force theminto 7 a slump condition.

In series with the switch 92, as shown schematically in FIG. 1 of thedrawings, is a cam operated switch 118 which is operated by a rotary cam120 driven in unison with the controls of the high production concreteproducing machine which delivers concrete blocks on the pallet 26 andwhich is coupled to intermittently activate the conveyor belts 24 on therollers 22.

This cam 120 is provided with a lobe 122 which is disposed to close theswitch 118 and also a holding coil switch 124 which energizes a holdingcoil 125 so that the switch 118 is held closed until the switch 92 isopened.

A conductor 126 is provided to interconnect the solenoid valve 106 andthe switch 118 when closed and another conductor 128 is coupled to oneend of the holding coil 125 and is also coupled to the solenoid valve106.

The slump block producing machine of the invention operatessubstantially as follows:

Concrete blocks of conventional shape are produced by the highproduction concrete block producing machine and are delivered on theconveyor belt 24 on the upper sides of pallets 26. The concrete blocksdelivered by the machine are preferably made of a high slump materialwhich includes slightly more moisture than the usual mix used to produceconventional concrete block.

The production machine is set so that its compression head stops at aposition to produce blocks which are a fraction of an inch taller thanthe conventional blocks of a standard modulus. It is desirable thatthese blocks are, for example, three eighths of an inch taller thanstandard blocks to allow for compression and slumping thereof.

As shown in FIG. 3 of the drawings, the blocks delivered on the pallet26 have an upper surface represented by the broken line C and sidesurfaces represented by broken lines D.

Several such concrete blocks are delivered on a pallet 26 by means ofthe belts 24 and when the pallet 26 approaches the pallet engagingmembers 48 and 50, the cam lobe 122, as shown in FIG. 1 of the drawings,also approaches the actuating point in its cycle wherein the switch 118is closed.

As the pallet 26 carrying the blocks moves over the engaging members 48and 50 of the vibrators 38 and 40, it also moves under the pressureplate 54.

When the lobe 122 of the cam 120 closes the switch 118, the solenoidvalve 106 is energized to an open position and compressed air isfurnished to the vibrators 38 and 40 and the vibrators 72 and 74. Also,the piston 114 in the cylinder 62 is forced downwardly carrying thepressure plate frame 56 and the pressure plate 54. This pressure plate54 is disposed in suspended swingable position by the pivotal bolt 64,as hereinbefore described, and the lower ends of the springs 82 engagethe rails 78 and 80 as the pressure plate closely approaches the uppersurfaces of the concrete blocks on the pallet 26. While the pressureplate is moved downwardly, it contacts the upper surfaces C of theblocks and gradually, with aid of vibra tion supplied by the vibrators,the block is compressed to a slump condition wherein its upper surfaceis disposed at F and its sides are caused unevenly to bow out intosomewhat convex wall structures G and H as shown in FIG. 3 of thedrawings. Thus, the slump block is formed by vibration and pressure in afree standing position on the pallet on which it was originally formedby the high production concrete block machine. It will be seen that thismethod may be carried out substantially in accordance with the cyclerate of the production machine and that the conventional conveyor belt24 may be slightly compressed when pressure is applied to these blockswhereby compression of the belts permits the pallet 26 to rest on thebars 28 which solidly support the pallet during compression slumping ofthe blocks thereon.

When the pressure plate 54 has been forced downwardly to a predeterminedposition to locate the upper surface of the blocks at the level F, shownin FIG. 3 of the drawings, the roller 94 of the limit switch 92 iscontacted by the end portion 100 of the arm 96 thereby opening theswitch 92 and deenergizing the holding coil 125 which permits the switch118 to open and deenergize the solenoid valve 106.

When the solenoid valve is deenergized, it closes and regulatedpressure, acting on the lower side 112 of the piston 114, forces thepiston upwardly which causes compressed air on the upper side 116 of thepiston to be forced out of the cylinder 62 and through the tube 102 andtube 42 through the vibrators 38, 40, 72 and 74. Thus, the plunger 58 isretracted together with the frame 56 'while the four coil springs 70tend normally to hold the frame 56 in substantially level position sothat it approaches the concrete blocks in a substantially level positionas it moves downward to engage the upper surfaces thereof. It will beunderstood that the rails 28 provide a positive stop for downwardmovement of the pallet 26, when under pressure, while the ends of theadjustment screws 76 provide a positive stop for the downward movementof the pressure plate 54 whereby, a precise height of the slump block iscon-trolled so that the distance between the upper surface F and thelower surface K is accurately controlled.

It will be appreciated that the present invention includes a method ofproducing slump blocks comprising; the production of conventionalconcrete blocks by a high production machine and permitting said highproduction machine to produce a block substantially taller than theultimate elevation of the slump block. Then delivering the productionconcrete block from the machine and applying vertical pressure andvibration to said conventional block until it is compressed andexternally bowed or deformed into a slump block configuration. Said 6pressure and vibration is stopped when the elevation of the slump blockis at a desired dimension which is substantially less than the originaldimension, or height of the conventional concrete block originallyproduced by the high production concrete block machine.

The method also comprises the subjection of the blocks to vibration ofthe pallet as well as vibration of a pressure plate on the uppersurfaces of the blocks while the pallet is supported or restrainedvertically and while the pressure plate moves downwardly concurrentlywith vibration thereof.

It has been found that the pressure plate 54 may be made of variousmaterials, however, plexiglass has been found most suitable since theusual concrete mix does not tend to adhere thereto as readily as it doesto other known materials. Additionally, during the process of making theblocks, it has been found that intermittent swabbing of the lowersurface of the pressure plate alleviates the tendency of the uppersurfaces of the blocks to leave deposits on lower surface of the plate54. The swabbing operation may include the application of a slight filmor coat of oil by any suitable swabbing device.

Since the pressure plate 54 is only momentarily engaged with the uppersurfaces of the concrete blocks, it will be recognized that the swabbingof this plate comprises a method step which is important in accordancewith the foregoing method in high production of slump blocks whenproduced from conventional concrete blocks delivered from a highproduction machine. Thus, the method includes the application ofpressure by a pressure plate on the upper surfaces of the blocks; thepressure plate being conditioned so that it does not adhere to the uppersurfaces of the blocks.

It will be obvious to those skilled in the art that variousmodifications of the slump block producing machine and method of theinvention may be resorted to in a manner limited only by a justinterpretation of the following claims.

We claim:

1. In a slump block producing machine the combination of: adelivery'conveyor of a conventional high production concrete blockmachine; a vertically movable pressure plate disposed above saidconveyor and adapted vertically to move into engagement with the uppersurfaces of concrete blocks disposed on a pallet carried by saidconveyor; actuating means coupled to said pressure plate and supportingthe same; a frame for supporting said actuating means whereby saidpressure plate is suspended thereby; said actuating means pivoted tosaid last mentioned frame so that the plane of said pressure plate isreadily conformable to the planes of concrete blocks supported on apallet therebelow; first vibrating means disposed to vibrate a pallet onsaid conveyor below said pressure plate; and second vibrating meanscoupled with said pressure plate for vibrating it; first means operableby a high production concrete block machine in connection with saidconveyor said first means coupled to said actuating means and said firstand second vibrating means for automatically initiating operation ofsaid pressure plate actuating means and said first and second vibratingmeans; limit switch means disposed to be actuated in accordance withdownward movement of said pressure plate for deenergizing said actuatingmeans and said first and second vibrator means when said pressure platereaches a predetermined vertical position; stop means in connection withsaid pressure plate; members stationarily disposed to be engaged by saidstop means for mechanically limiting the downward travel of saidpressure plate, said conveyor comprising compressible belts supporting apallet thereon and bars slightly below the upper surfaces of said beltsdisposed to support the lower surface of a pallet when said pressureplate engages and compresses blocks on the upper surface thereof.

2. In a slump block producing machine the combination of: a deliveryconveyor of a conventional high production concrete block machine; avertically movable pres sure plate disposed above said conveyor andadapted vertically to move into engagement with the upper surfaces ofconcrete blocks disposed on a pallet carried by said conveyor; actuatingmeans coupled to said pressure plate and supporting the same; a framefor supporting said actuating means whereby said pressure plate issuspended thereby; said actuating means pivoted to said last mentionedframe so that the plane of said pressure plate is readily conformable tothe planes of concrete blocks supported on a pallet therebelow; firstvibrating means disposed to vibrate a pallet on said conveyor below saidpressure plate; and second vibrating means coupled with said pressureplate for vibrating it; first means operable by a high productionconcrete block machine in connection with said conveyor said first meanscoupled to said actuating means and said first and second vibratingmeans for automatically initiating operation of said pressure plateactuating means and said first and second vibrating means; limit switchmeans disposed to be actuated in accordance with downward movement ofsaid pressure plate for deenergizing said actuating means and said firstand second vibrator means when said pressure plate reaches apredetermined vertical position; stop means in connection with saidpressure plate; members stationarily disposed to be engaged by said stopmeans for mechanically limiting the downward travel of said pressureplate, said conveyor comprising compressible belts supporting a palletthereon and means slightly below the upper surfaces of said beltsdisposed to support the lower surface of a pallet when said pressureplate engages and compresses blocks on the upper surface thereof, saidactuating means being a pneumatic cylinder having a plunger supportingsaid pressure plate; said vibrators also being pneumatically powered;solenoid valve means coupled to said first means for energizing saidactuating means and said vibrators.

3. In a slump block producing machine, the combination of: a deliveryconveyor of a conventional high production concrete block machine; avertically movable pressure plate disposed above said conveyor andadapted vertically to move into engagement with upper surfaces ofconcrete blocks disposed on a pallet carried by said con veyor;actuating means coupled to said pressure plate for actuating the saidpressure plate upwardly and downwardly; a frame for supporting saidactuating means and said pressure plate; first vibrating means freelyengageable with the bottom of a pallet on said conveyor and,

8 disposed to vibrate said pal-let on said conveyor; and second meanscoupled with said pressure plate for vibrating it; said first vibratingmeans pivotally mounted on a substantially horizontal axis adjacent saidconveyor and having means norm-ally disposed above a lower surface of apallet on said conveyor and, engageable with the lower surface of apallet on said conveyor whereby said pallet when moved along on saidconveyor pivots said last mentioned means downwardly about saidhorizontal axis and engages said last mentioned means with the bottom ofsaid pallet.

'4. In a slump block producing machine, the combination of: a deliveryconveyor of a conventional high production concrete block machine; avertically movable pressure plate disposed above said conveyor andadapted vertically to move into engagement with upper surfaces ofconcrete blocks disposed on a pallet carried by said conveyor; actuatingmeans coupled to said pressure plate for actuating the said pressureplate upwardly and downwardly; a frame for supporting said actuatingmeans and said pressure plate; first vibrating means freely engageablewith the bottom of a pallet on said conveyor and, disposed to vibratesaid pallet on said conveyor; and second means coupled with saidpressure plate for vibrating it; said conveyor having compressible beltmeans disposed to carry pallets thereon; and further means slightlybelow the upper surfaces of said belts disposed to provide supportingstops for the lower surfaces of a pallet when said pressure plateengages blocks on a pallet carried by said belt means and thereby causescompression thereof.

References Cited by the Examiner UNITED STATES PATENTS Re. 24,527 8/1958Ripley 25155 288,240 11/1883 =Ittner 25-122 876,388 1/1908 Nieters.

1,787,449 1/1931 Jackson.

1,905,975 4/ 1933 Thomas.

2,431,034 11/ 1947 Gelbman.

2, 6=85,1 1'6 '8/ 1954 Schutt.

ROBERT F. WHITE, Primary Examiner.

MICHAEL V. BRINDI'SI, ALEXANDER H. BROD- MERKEL, Examiners.

R. B. MOFFITI, Assistant Examiner.

1. IN A SLUMP BLOCK PRODUCING MACHINE THE COMBINATION OF: A DELIVERYCONVEYOR OF A CONVENTIONAL HIGH PRODUCTION CONCRETE BLOCK MACHINE; AVERTICALLY MOVABLE PRESSURE PLATE DISPOSED ABOVE SAID CONVEYOR ANDADAPTED VERTICALLY TO MOVE INTO ENGAGEMENT WITH THE UPPER SURFACES OFCONCRETE BLOCKS DISPOSED ON A PALLET CARRIED BY SAID CONVEYOR; ACTUATINGMEANS COUPLED TO SAID PRESSURE PLATE AND SUPPORTING THE SAME; A FRAMEFOR SUPPORTING SAID ACTUATING MEANS WHEREBY SAID PRESSURE PLAT ISSUSPENDED THEREBY; SAID ACTUATING MEANS PIVOTED TO SAID LAST MEMTIONEDFRAME SO THAT THE PLANE OF SAID PRESSURE PLATE IS READILY CONFORMABLE TOTHE PLANES OF CONCRETE BLOCKS SUPPORTED ON A PALLET THEREBELOW; FIRSTVIBRATING MEANS DISPOSED TO VIBRATE A PALLET ON SAID CONVEYOR BELOW SAIDPRESSURE PLATE; AND SECOND VIBRATING MEANS COUPLED WITH SAID PRESSUREPLATE FOR VIBRATING IT; FIRST MEANS OPERABLE BY A HIGH PRODUCTIONCONCRETE BLOCK MACHINE IN CONNECTION WITH SAID CONVEYOR SAID FIRST MEANSCOUPLED TO SAID ACTUATING MEANS AND SAID FIRST AND SECOND VIBRATINGMEANS FOR AUTOMATICALLY INITIATING OPERATION OF SAID PRESSURE PLATEACTUATING MEANS AND SAID FIRST AND SECOND VIBRATING MEANS; LIMIT SWITCHMEANS DISPOSED TO BE ACTUATED IN ACCORDANCE WITH DOWNWARD MOVEMENT OFSAID PRESSURE PLATE FOR DEENERGIZING SAID ACTUATING MEANS AND SAID FIRSTAND SECOND VIBRATOR MEANS WHEN SAID PRESSURE PLATE REACHES APREDETERMINED VERTICAL POSITION; STOP MEANS IN CONNECTION WITH SAIDPRESSURE PLATE; MEMBERS STAIONARILY DISPOSED TO THE ENGAGED BY SAID STOPMEANS FOR MECHANICALLY LIMITING THE DOWNWARD TRAVEL OF SAID PRESSUREPLATE, SAID CONVEYOR COMPRISING COMPRESSIBLE BELTS SUPPORTING A PALLETTHEREON AND BARS SLIGHTLY BELOW THE UPPER SURFACES OF SAID BELTSDISPOSED TO SUPPORT THE LOWER SURFACE OF A PALLET WHEN SAID PRESSUREPLATE ENGAGES AND COMPRESSES BLOCKS ON THE UPPER SURFACE THEREOF.